The present invention generally relates to a flanged steel wheel having either single or dual flanges as typically used on tracked transportation vehicles such as railway locomotives and rolling stock, shipyard and port gantry cranes, industrial bridge cranes, mining cars transit cars or any other material handling or transportation application. More specifically the present invention relates to an improved composite structure for the flanged portion of both single and dual flanged wheels.
Although the present invention is equally applicable to single flanged steel wheels, it is particularly useful on dual flanged steel wheels typically used in industrial gantry and bridge cranes that traverse fixed, parallel rails, of finite length. In such industrial applications, because of the typical asymmetrical loading of the gantry or bridge crane, the vertical plane of the flanged wheel frequently becomes askew to the direction of the rails whereby the wheel flange contacts the side of the rail causing frictional erosion of the flange thickness. As a result of such flange erosion, the flange thickness is progressively diminished whereby the wheel flange may fail causing possible derailment of the tracked vehicle.
Heretofore attempts have been made to solve the wheel flange erosion problem by manufacturing the wheels from hardened steel whereby the wheel flange could withstand the lateral forces applied to it resulting from flange-rail contact and in an attempt to slow the rate of frictional erosion of the flange. Another solution has been to reduce the frictional forces between rail and wheel flange by application of a lubricant to the wheel flange, or to the side of the rail, without the lubricant finding its way to the to the top of the rail or to the wheels""tread surface.
Either method has its own unique maintenance requirements. The hardened steel wheel must be frequently inspected for frictional erosion upon the wheel flange so that the wheel may be replaced before the wheel flange fails. The rail and/or wheel flange lubrication method requires inspection and maintenance to keep the lubrication supply replenished and requires proper alignment and maintenance of the lubrication dispensing system to assure that the lubricant is not applied to the top of the rail or the wheel tread surface whereby desired frictional contact, between rail and wheel tread is sacrificed.
The prior art has long recognized the diverse property requirements between the wheel tread and wheel flange for steel wheels operating on a steel rail, particularly where the wheel is a driving wheel. The tread requiring high traction, or a high coefficient of friction, and the flange requiring high strength and a low coefficient of friction. Therefore, manufacturing the wheel from a unitary base material is not necessarily desirable. To solve the diverse material property problem, between the wheel flange and wheel tread, the prior art devised mechanical techniques whereby the wheel body, tread and flange comprise different materials as evidenced by the following prior art patents:
U.S. Pat. No. 307,927 teaches a composite wheel having a cast iron facing circumscribing the tread area of the wheel and extending radially outward to cover the inside surface of the wheel flange.
U.S. Pat. No. 547,096 teaches a main body, including the wheel flange, manufactured from cast iron and having a forged or rolled steel hoop inserted into the main body forming the tread area of the wheel.
U.S. Pat. No. 560,161 teaches a wheel having a variable distribution of carbon comprising a tough metal substrate, such as low-carbon steel, and having an external stratum comprising the wheel tread which is composed of a relatively high-carbon steel. The inside surface of the flange, adjacent the wheel tread, is disclosed as xe2x80x9csomewhat less hard.xe2x80x9d
U.S. Pat. No. 2,030,243 teaches a composite wheel having a main body substrate wherein there are two circumscribing bands of differing materials. One band includes the inside half of the wheel flange and one half of the tread. The second band forms the remaining half of the wheel tread. The first band comprises a high resistance material and the second band is made of a softer material.
U.S. Pat. No. 3,272,550 teaches a composite wheel structure wherein the wheel flange and the main body of the wheel are of the same material. An xe2x80x9cannular outer skin,xe2x80x9d having a modulus of elasticity lower than that of the rail circumscribes the tread area of the wheel.
U.S. Pat. No. 4,310,191 teaches a composite wheel wherein the main body of the wheel includes the wheel flange, and a rim of high friction material circumscribes the tread area of the wheel.
U.S. Pat. No. 4,638,540 teaches a composite wheel having a main body substrate material having separate inlaid materials for the wheel tread and the inside surface of the wheel flange.
U.S. Pat. No. 6,073,346 teaches a wheel having a main body substrate material, including the outer half of the wheel flange, a circumscribing hoop forming the wheel tread and inside half of the wheel flange. It is proposed that the hoop be made of a high frictional material for locomotive wheels and a low frictional material for railroad rolling stock wheels. The hoop forming the tread and inside half of the flange are made from powdered metal, hot isostaticly pressed in place about the wheel substrate.
The present invention provides a method by which the entire flanged railroad wheel may comprise a hardened steel material to adequately withstand the operating loads and forces typically acting upon such a wheel when in service. However, an overlay of metallic material is applied to the inside surface of the wheel""s flange thereby forming an annular band of low friction material circumscribing the inside surface of the wheel flange. The annular band of overlaid, low friction material is positioned in the area of the flange that engages the rail""s side surface. Typically the overlay material may comprise a cobalt or nickel based alloy, however any other suitable material may be used.